The present invention relates to a 3-dimentional imaging screen for multi-viewer, and in particular to a 3-dimentional imaging screen for simultaneously watching a 3-dimentional image by multi-viewer without wearing glasses, in which the screen comprises a beam dividing prism corresponding to a pixel on screen, the beam dividing prism dividing an incident beam on the screen into a vertical and/or horizontal direction according to the shape thereof.
It has been studied about a display device with which viewers may watch a conventional 2-dimentional image, such as television image, like a 3-dimentional image. In order to watch the conventional 3-dimentional image, the viewers generally wear a pair of polarized glasses which make the 3-dimentional image, by using a visual timing difference, from the 2-dimentional images which were made by using a plurality of cameras when taking images for a television program or movie.
For an example, the U.S. Pat. No. 4,559,556 discloses a system for viewing three dimentional images. The viewing system comprises a filter mat having two juxtaposed polarizing filters for placement over a television viewing screen or other rear surface projection device in substantial registry with two similarly juxtaposed and slightly different images of a common scene or subject. The polarizing filters are oriented on different axes to polarize the light from the two images on different axes. The viewer observes these polarized images through eyeglasses.
However, it has caused expenses and inconvenience according to the manufacturing the conventional 3-dimentional image and using glasses. In order to overcome the problems, there is developed a 3-dimentional image screen by a viewing zone recently, in which the 3-dimentional image screen by the viewing zone embodies the 3-dimentional image on the image incident screen itself, which enables a lot of viewer to watch the image without wearing the polarized glasses.
Preferably the viewing zone for displaying the 3-dimentional image should be generated as many as possible. For that reason, there is a method that a plurality of image incident devices are used as many as the viewing zones with use of such as a lenticular, a spherical reflective panel or a Fresnel lens for projecting the image. In addition, there is another method which uses a holographic screen for generating a plurality of viewing zones on a single screen.
The holographic screen uses a hologram serving as a kind of optical elements. When writing the hologram, the holographic screen writes several phases of an oriented object having diffrent direction on one hologram by multi-exposing with moving position of a photosensitive panel or the object, or with moving the position of the photosensitive panel and with changing the object itself.
The method for generating a plurality of viewing zones with use of a lenticular, a spherical reflective panel or a Fresnel lens can be easily embodied for providing the 3-dimensional image but not good in efficiency. Particularly, though it can enlarge size of screen for expanding the size of the viewing zone, the lenticular screen is still inefficient in fact that only a few viewers can watch the screen in comparison with the size of the screen.
In detail, the method for expanding size of the viewing zone with use of the lenticular screen may be achieved by enlarging the size of the lenticular lens and increasing the number of the images in different viewing directions. For example, assuming that a shoulder of a viewer has a width of about 40 cm, the viewing zone requires at least 80 cm width for two viewers to watch the 3-dimentional image at the same time. Assuming that a distance between eyes is 6.5 cm, at least 13 images having different viewing directions are required in order to form the 80 cm width viewing zones. Therefore, there is a technical limitation in that the number of the images having different viewing directions as well as the size of the projection lens should be continuously increased because the viewing zone size should be steadily increased by over 40 cm in order to increase the number of viewers at the same time.
Accordingly, the method to expand the size of the viewing zone among various methods for multi-viewer is not efficient comparing with the method increasing the number of the viewing zones.
In addition, multi-exposure hologram using the holographic screen also has some problems in a screen brightness because the diffraction efficiency decreases in an inverse proportion to a root value of the number of the multi-exposure.
The present invention is designed to solve the above problems. Therefore, on object of the present invention is to provide a 3-dimentional imaging screen for multi-viewer which maintains a proper screen brightness on the single screen such that a plurality of viewers can watch the screen at the same time, and which configures the number of the viewing zones according to the number of the viewers.
The object of the present invention is accomplished by providing a configuration of a screen, which can make the number of the viewing zone increased, resulting that the multi-viewer may watch the 3-dimentional image simultaneously.
The technical spirit of the present invention is achieved by using a prism panel together with a 3-dimentional image projection screen, in which the prism panel consists of an 1-dimentional or 2-dimentional array of prism cells which can disperse a projected image to each direction determined by each pixel.
In other words, the 3-dimentional imaging screen for multi-viewer which projects an object on the screen such that viewers watch a 3-dimentional image, wherein the screen comprises a 3-dimentional image projection screen positioned to a direction of an incident beam of the image, and a prism panel is formed with prism cell having a plurality of disperse surfaces of the incident beam on a rear surface of the 3-dimentional image projection screen, whereby the number of viewing zones is corresponding to the number of the disperse surfaces of the prism cell.
The prism panel is coupled to the rear surface of the 3-dimentional image projection screen, and the 3-dimentional image projection screen has enough thickness not to generate an interference effect such as a moir_interference pattern.
The prism panel is installed to the rear surface of the 3-dimentional image projection screen having a predetermined distance therebetween, and the distance between the 3-dimentional image projection screen and the prism panel is properly spaced apart not to generate the interference effect such as a moir_interference pattern.
The prism panel is formed and integrated to the rear surface of the 3-dimentional image projection screen in a emboss or engrave manner, and the 3-dimentional image projection screen has enough thickness not to generate the interference effect such as moir_interference pattern.